IAC Code p0505 2001 1500 5.9 gas 140000 miles

[mopar2904]

At this point I will take a guess if you think it might help. Idle Air system code did not come up with the original ECM, due to a failure I purchased a new ECM from Flagship One but with the replacement I can NOT get the code to go away. I have returned it to them and they stated that it tested OK and the issue was vehicle related. There are no sensors left to replace that I have not tried already (all engine sensors are new) I even took the Idle air control off of a vehicle that was known as good and the new IAC worked great on the other vehicle which leads me to believe that the IAC is not the problem. Now I have replaced every vacuum line on the vehicle and rechecked every electrical connection and removed the wiring looms to inspect all the wiring, still the code persists. I can start the vehicle and it seems to run fine at idle with no light on (after reset) but as soon as I turn the steering wheel or the air conditioner turns on or I touch the accelerator the light pops on and the same and only code pops up P0505. If there is any suggestion other than my original thought of burning the truck to the ground and cut my losses it would be appreciated.

 

[Slinge]

So do I understand correctly that you changed IAC motor ?
Did you buy a Mopar IAC ?

 

[Fast69Mopar]

At this point I will take a guess if you think it might help. Idle Air system code did not come up with the original ECM, due to a failure I purchased a new ECM from Flagship One but with the replacement I can NOT get the code to go away. I have returned it to them and they stated that it tested OK and the issue was vehicle related. There are no sensors left to replace that I have not tried already (all engine sensors are new) I even took the Idle air control off of a vehicle that was known as good and the new IAC worked great on the other vehicle which leads me to believe that the IAC is not the problem. Now I have replaced every vacuum line on the vehicle and rechecked every electrical connection and removed the wiring looms to inspect all the wiring, still the code persists. I can start the vehicle and it seems to run fine at idle with no light on (after reset) but as soon as I turn the steering wheel or the air conditioner turns on or I touch the accelerator the light pops on and the same and only code pops up P0505. If there is any suggestion other than my original thought of burning the truck to the ground and cut my losses it would be appreciated.

This is where a scan tool could help you identify if you have a PCM issue, a wiring issue or an IAC issue. If you have a proper scan tool with true bi-directional capabilities, remove the Idle Air Control motor and actuate the motor and watch it and see if it moves when commanded.

If the IAC does not move when commanded disconnect the IAC and get out your DVOM and probe the IAC connector and monitor the voltage while actuating the IAC. This way you can verify if the PCM is sending the proper voltage to the IAC through the wiring harness.

 

[mopar2904]

Looking into a bi-directional scan tool now. The one I have is a bit old and only reading the code and that seems to be a generic code for the IAC system. BUT when I plugged another new one in NOT installed I could feel it pulsing but it didn’t move. It seems to run fine up to 3700 RPM and then it starts popping and jerking.

 

[Fast69Mopar]

Looking into a bi-directional scan tool now. The one I have is a bit old and only reading the code and that seems to be a generic code for the IAC system. BUT when I plugged another new one in NOT installed I could feel it pulsing but it didn’t move. It seems to run fine up to 3700 RPM and then it starts popping and jerking.

Have you used a DVOM to verify you have a good ground at the IAC connector?

What is the voltage on the pins in the connector with the IAC disconnected?